.jshintrc

black: make codebase compatible with black v21.4b2 and v20.8b1

I don't know what exact version of black made it care about these whitespace
differences, but this is the version I got when I just installed it with
`pip3 install black`.

I'm intentionally not increasing the version of black required, as I don't want
to force everyone to upgrade their version of black, and these fixes are
backwards compatible with black v20.8b1. If there are more issues in the future
and this becomes a maintenance burden I may do so in a future change.

Tested with both versions of black (I got the older version via
`pip3 install black==20.8b1`)

Differential Revision: https://phab.mercurial-scm.org/D10539

{
    // Enforcing
    "eqeqeq"        : true,     // true: Require triple equals (===) for comparison
    "forin"         : true,     // true: Require filtering for..in loops with obj.hasOwnProperty()
    "freeze"        : true,     // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
    "nonbsp"        : true,     // true: Prohibit "non-breaking whitespace" characters.
    "undef"         : true,     // true: Require all non-global variables to be declared (prevents global leaks)

    // Environments
    "browser"       : true      // Web Browser (window, document, etc)
}